1/26. Interaction of genetic predisposition and environmental factors in the pathogenesis of idiopathic orthostatic intolerance.BACKGROUND: The hemodynamic and autonomic abnormalities in idiopathic orthostatic intolerance (IOI) have been studied extensively. However, the mechanisms underlying these abnormalities are not understood. If genetic predisposition were important in the pathogenesis of IOI, monozygotic twins of patients with IOI should have similar hemodynamic and autonomic abnormalities. methods: We studied two patients with IOI and their identical twins. Both siblings in the first twin pair had orthostatic symptoms, significant orthostatic tachycardia, increased plasma norepinephrine levels with standing, and a greater than normal decrease in systolic blood pressure with trimethaphan infusion. RESULTS: Both siblings had a normal response of plasma renin activity to upright posture. In the second twin pair, only one sibling had symptoms of orthostatic intolerance, an orthostatic tachycardia, and raised plasma catecholamines with standing. The affected sibling had inappropriately low plasma renin activity with standing and was 8-fold more sensitive to the pressor effect of phenylephrine than the unaffected sibling. CONCLUSIONS: We conclude that in some patients, IOI seems to be strongly influenced by genetic factors. In others, however, IOI may be mainly caused by nongenetic factors. These findings suggest that IOI is heterogenous, and that both genetic and environmental factors contribute individually or collectively to create the IOI phenotype.- - - - - - - - - - ranking = 1keywords = pressure (Clic here for more details about this article) |
2/26. Neurovascular lessons from a pair of identical twins with cerebral aneurysms.A pair of hypertensive identical twins are reported, one of whom was non-compliant with her antihypertension medication, and after a subarachnoid haemorrhage was found to have multiple cerebral aneurysms. The other asymptomatic compliant twin was noted to have only a single small cerebral aneurysm. As both identical twins are likely to share the same cerebral vascular architecture it is suggested that good control of blood pressure contributed to the cerebral vascular integrity of the asymptomatic twin. This is the first report on the role of blood pressure in the formation of cerebral aneurysms and provides insights for an alternative approach to the controversial management of asymptomatic cerebral aneurysms.- - - - - - - - - - ranking = 2keywords = pressure (Clic here for more details about this article) |
3/26. The smile in anencephalic infants.During the period 1947-1959 twelve new-born mero-anencephalics were observed, who survived for more than 1 day after birth. Two even lived for 20 and 237 days, respectively. In 4 of the 12 children studied touching or slight pressure, and also faradic stimulation of various spots of the cerebro-vascular area were invariably followed by a facial expression which was very similar to smiling. Movies of it were shown to groups of impartial observers. In 78% the facial expression was judged to be a smile, a laugh or a grin. The neuroanatomical finding of a largely intact pontine tegmentum as being the most rostrally situated identifiable structure of the brainstem, has led to the hypothesis that the neural mechanisms underlying the smile are localized in the pontine tegmentum.- - - - - - - - - - ranking = 1keywords = pressure (Clic here for more details about this article) |
4/26. Functionally atrialized parchment-like right ventricle with extensive myocardial fibrosis of left ventricle.A 18-year-old female with unusual type of parchment-like right ventricle died of intractable congestive heart failure was reported. A catheter study revealed the absence of systolic contraction of the right ventricle. The pressure tracing curve in the right ventricle was virtually the same as in the right atrium. At autopsy, there was an extensive myocardial fibrosis of the left ventricle in addition to the almost total absence of the myocardium of the right ventricle. The case was considered to be a unique type of idiopathic cardiomyopathy.- - - - - - - - - - ranking = 1keywords = pressure (Clic here for more details about this article) |
5/26. Care and management of the child with shunted hydrocephalus.This article reviews the physiology of cerebrospinal fluid formation and flow, the causes of hydrocephalus in the pediatric patient, symptoms of increased intracranial pressure, recent advances in shunt technology, the medical and surgical management of hydrocephalus, and potential complications of ventricular shunting devices. nursing care in the post-operative period and for the child with shunt malfunction is discussed, as well as the long-term management needs and anticipatory guidance issues as related to a child with a ventricular shunting device. A case study of an infant with hydrocephalus illustrates key concepts.- - - - - - - - - - ranking = 1keywords = pressure (Clic here for more details about this article) |
6/26. Steroid responsive familial neuropathy with liability to pressure palsies.Autosomal dominant motor and sensory neuropathy with liability to pressure palsies was studied in three members of the same family. Only one of two monozygotic twin sisters was clinically affected. She developed unilateral peroneal palsy twenty minutes following local pressure. electromyography revealed a weak intermediate innervation pattern with very rapid action potentials in the right anterior lower leg muscle. A 25-70 per cent reduction of motor and sensory conduction velocity was recorded in the clinically unaffected twin sister and in the father. The electrophysiological findings in the mother were normal. The sural nerve biopsy revealed "sausage-like" formations. The palsy persisted for two months and disappeared after eight weeks of fluocortolon treatment. It is possible that the myelin sheaths acted as antigen.- - - - - - - - - - ranking = 6keywords = pressure (Clic here for more details about this article) |
7/26. Carotid arteriosclerosis in identical twins discordant for cigarette smoking.From a nationwide twin panel, identical twin pairs with highest discordance in cigarette smoking were selected for a study of arteriosclerosis (49 pairs with a mean age of 52 years). smoking history was obtained in 1975, 1981, and 1986. The mean life-long smoking dose of the smoking cotwins was 20 package-years. The smoking and nonsmoking cotwins had similar systolic and diastolic blood pressures, total plasma cholesterol level, body mass index, and some psychosocial factors; the only difference was found in use of alcohol, which was greater among smoking cotwins. Duplex sonography of carotid arteries was performed. Carotid artery stenoses (narrowing of area of the lumen with 15-60%) were found in nine pairs: in nine smoking twins and in two of their nonsmoking cotwins (p = 0.036). The total area of carotid plaques was 3.2 times larger in smoking cotwins (p less than 0.001). The thickness of the inner layer of carotid arteries was more marked in smoking cotwins (p less than 0.001). The size of plaques and the degree of inner layer thickening correlated with the dose of smoking (NS). The association of smoking with carotid arteriosclerosis was highly significant even after the adjustment for age, total plasma cholesterol level, diastolic blood pressure, and body mass index in multiple logistic regression analyses.- - - - - - - - - - ranking = 2keywords = pressure (Clic here for more details about this article) |
8/26. Familial pseudotumor cerebri in male heterozygous twins.papilledema due to raised intracranial pressure in absence of intracranial mass arose roughly at the same time in 2 male heterozygous twins. The diagnosis of benign intracranial hypertension (BIH) was confirmed by the finding of normal cerebrospinal fluid and high opening pressure. neurologic examination was normal. In both cases choroidal folds were evident. The relationship between BIH and genetic factors is discussed.- - - - - - - - - - ranking = 2keywords = pressure (Clic here for more details about this article) |
9/26. Optic glioma with progressive occlusion of the aqueduct of Sylvius in monozygotic twins with neurofibromatosis.Monozygotic twins sisters with optic glioma "in mirror image" (one with involvement of the left optic nerve and the other with the right optic nerve) and hydrocephalus secondary to progressive stenosis of the aqueduct have been found in a series of 128 cases below 14 years of age with neurofibromatosis. The optic glioma was diagnosed in each of the twins at 2 years of age. In one twin the tumor involved only the optic nerve but in the other the glioma affected the optic nerve and spread to the homolateral zone of the optic chiasm. First symptoms of hydrocephalus appeared at 8 years and 11 years of age respectively but ventriculo-peritoneal shunting procedures were performed to relieve intracranial hypertension at 11 years and 15 years of age respectively. At 2 years of age both twins had pneumoencephalography which demonstrated normal air passage through the aqueduct and cerebral ventricles of normal size and morphology. Posterior studies with CT-scan demonstrated progressive obstruction of the aqueduct with very slow progression of the hydrocephalus in each twin, although it was not observed simultaneously. The increased intracranial pressure was tolerated for many years in each twin without obvious symptoms which could be attributed to the slow progression of the aqueduct obstruction.- - - - - - - - - - ranking = 1keywords = pressure (Clic here for more details about this article) |
10/26. Infantile glaucoma in Down's syndrome (trisomy 21).We examined five patients with Down's syndrome and bilateral infantile glaucoma. In the first few months of life four patients had large cloudy corneas, breaks in Descemet's membrane, increased intraocular pressure, photophobia, and tearing. In one patient the diagnosis was delayed until 3 1/2 years of age because of concomitant nasolacrimal duct obstruction. Two patients developed cataracts and retinal detachment and have undergone multiple surgical procedures. The clinical course in these two older patients suggests that coexistence of congenital glaucoma, severe myopia, and cataracts in patients with trisomy 21 strongly predisposes for the development of retinal detachment and poor visual outcome.- - - - - - - - - - ranking = 1keywords = pressure (Clic here for more details about this article) |
| | Next -> |